Electric power charge and discharge system

ABSTRACT

An electric power charge and discharge system for an electronic device having a battery, by which the electronic device can be used for a long period of time. In a wireless communication device including a wireless driving portion including a first battery and a wireless charging portion including a second battery, the first battery is charged by electric power from a fixed power supply and the second battery is charged by using electromagnetic waves existing in an external space. Further, the first battery and the second battery are discharged alternately, and during a period in which the first battery is discharged, the second battery is charged.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an electric power charge and dischargesystem. In particular, the present invention relates to an electricpower charge and discharge system which supplies electric power to abattery noncontactly by receiving a wireless signal.

2. Description of the Related Art

Various electronic devices are coming into wide use, and a wide varietyof products are in the marketplace. In particular, in recent years, thespread of portable electronic devices for outdoor use has beenremarkable. For example, mobile phones, digital video cameras, and thelike have become very convenient because of high-definition displayportions, increased durability of batteries, and further reduction inpower consumption. A portable electronic device has a structure in whicha battery that is a charging means is incorporated. Power source voltagefor driving the portable electronic device can be ensured by thebattery. As the battery, a secondary battery such as a lithium ionbattery has been used, and the battery has been charged directly from anAC adaptor which is plugged into an AC power supply which is wiredinside a building or the like (hereinafter referred to as a fixed powersupply) (see Patent Document 1: Japanese Published Patent ApplicationNo. 2005-150022).

In addition, research on simple charging of a battery with a noncontactmeans, in which electromagnetic coupling is used with an externalelectric power supply means has been performed (see Patent Document 2:Japanese Published Patent Application No. 2001-190029).

However, while the frequency in use of electronic devices such as mobilephones, digital video cameras, and the like has been rising and thedemand for improvement of hours of use of a battery has been increasing,improvement of charging capability of the battery in accordance with thehours of use of the battery has limitations. Further, the AC adaptor forcharging the battery which is a power supply incorporated in such amobile phone, a digital video camera, or the like is too large to becarried along easily.

Further, noncontact charging utilizing electromagnetic coupling can beperformed only in the periphery of a battery charger, and moreover,electric power is needed to be supplied from a fixed power supply.Therefore, it may be necessary to carry the battery charger along, andthe burden caused by doing so remains.

In addition, unlike the case where electric power is supplied from afixed power supply, the electronic devices having the batterycontinuously consume electric power accumulated in the battery and thehours of use has limitations. Therefore, there is a problem in thatimprovement of hours of use of the battery largely depends on theimprovement of charging capability of the battery and long hours of useof the electronic devices has limitations.

SUMMARY OF THE INVENTION

In view of the above, it is an object of the present invention toprovide an electric power charge and discharge system for an electronicdevice having a battery, by which the electronic device can be used fora long period of time.

In order to solve the foregoing problems, according to the electricpower charge and discharge system of the present invention, in awireless communication device including a wireless driving portionincluding a first battery and a wireless charging portion including asecond battery, the first battery is charged by electric power from afixed power supply and the second battery is charged by usingelectromagnetic waves existing in an external space. Further, the firstbattery and the second battery are discharged alternately, and during aperiod in which the first battery is discharged, the second battery ischarged.

According to one feature of the electric power charge and dischargesystem of the present invention, in a wireless communication deviceincluding a wireless driving portion including a first battery which ischarged by electric power from a fixed power supply and a wirelesscharging portion including a second battery which is charged by usingelectromagnetic waves existing in an external space, the first batteryand the second battery are discharged alternately, and during a periodin which the first battery is discharged, the second battery is charged.

According to another feature of the electric power charge and dischargesystem of the present invention, in a wireless communication deviceincluding a wireless driving portion including a first battery which ischarged by electric power from a fixed power supply and a wirelesscharging portion including a second battery which is charged by usingelectromagnetic waves existing in an external space, an antenna forreceiving the electromagnetic waves in the wireless charging portiondoubles as an antenna for transmitting and receiving an external signalin the wireless driving portion; the first battery and the secondbattery are discharged alternately; and during a period in which thefirst battery is discharged, the second battery is charged.

According to another feature of the electric power charge and dischargesystem of the present invention, in a wireless communication deviceincluding a wireless driving portion including a first battery which ischarged by electric power from a fixed power supply and a wirelesscharging portion including a second battery which is charged by usingelectromagnetic waves existing in an external space, an antenna forreceiving the electromagnetic waves in the wireless charging portion isprovided in the wireless charging portion separately from an antenna fortransmitting and receiving an external signal in the wireless drivingportion; the first battery and the second battery are dischargedalternately; and during a period in which the first battery isdischarged, the second battery is charged.

According to another feature of the electric power charge and dischargesystem of the present invention, in a wireless communication deviceincluding a wireless driving portion including a first battery which ischarged by electric power from a fixed power supply and a wirelesscharging portion including a second battery which is charged by usingelectromagnetic waves existing in an external space, an antenna forreceiving the electromagnetic waves in the wireless charging portiondoubles as an antenna for transmitting and receiving an external signalin the wireless driving portion; the first battery and the secondbattery are discharged alternately; during a period in which the firstbattery is discharged, the second battery is charged; and a chargeswitching circuit for switching such that the second battery is chargedby electric power from the fixed power supply during a period in whichthe wireless driving portion is connected to the fixed power supply isprovided.

According to another feature of the electric power charge and dischargesystem of the present invention, in a wireless communication deviceincluding a wireless driving portion including a first battery which ischarged by electric power from a fixed power supply and a wirelesscharging portion including a second battery which is charged by usingelectromagnetic waves existing in an external space, an antenna forreceiving the electromagnetic waves in the wireless charging portion isprovided in the wireless charging portion separately from an antenna fortransmitting and receiving an external signal in the wireless drivingportion; the first battery and the second battery are dischargedalternately; during a period in which the first battery is discharged,the second battery is charged; and a charge switching circuit forswitching such that the second battery is charged by electric power fromthe fixed power supply during a period in which the wireless drivingportion is connected to the fixed power supply is provided.

According to another feature of the electric power charge and dischargesystem of the present invention, in a wireless communication deviceincluding a wireless driving portion including a first battery which ischarged by electric power from a fixed power supply and a wirelesscharging portion including a second battery which is charged by usingelectromagnetic waves existing in an external space, an antenna forreceiving the electromagnetic waves in the wireless charging portion isan external antenna for transmitting and receiving an external signal inthe wireless driving portion; the first battery and the second batteryare discharged alternately; and during a period in which the firstbattery is discharged, the second battery is charged.

According to another feature of the electric power charge and dischargesystem of the present invention, in a wireless communication deviceincluding a wireless driving portion including a first battery which ischarged by electric power from a fixed power supply and a wirelesscharging portion including a second battery which is charged by usingelectromagnetic waves existing in an external space, an antenna forreceiving the electromagnetic waves in the wireless charging portion isan external antenna for transmitting and receiving an external signal inthe wireless driving portion; the first battery and the second batteryare discharged alternately; during a period in which the first batteryis discharged, the second battery is charged; and a charge switchingcircuit for switching such that the second battery is charged byelectric power from the fixed power supply during a period in which thewireless driving portion is connected to the fixed power supply isprovided.

Further, the wireless driving portion of the present invention may beprovided with a charge controlling circuit for controlling charging tothe first battery.

Further, the wireless charging portion of the present invention mayinclude an internal circuit and may be provided with a power supplyswitching circuit for switching between electric power from the firstbattery and the second battery, which is supplied to the internalcircuit.

Further, the wireless charging portion of the present invention may beprovided with a wireless charge controlling circuit for controllingcharging to the second battery.

By the electric power charge and discharge system of the presentinvention, improvement in the hours of use of a battery can be achieved.Therefore, the frequency of carrying along an AC adapter for chargingthe battery can be reduced.

Further, by the electric power charge and discharge system of thepresent invention, a battery can be charged noncontactly without using abattery charger. Therefore, an electronic device can be driven even inthe state where an AC adapter for charging the battery does not exist.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram showing a structure of Embodiment Mode 1.

FIG. 2 is a chart describing the structure of Embodiment Mode 1.

FIGS. 3A to 3C are diagrams describing the structure of Embodiment Mode1.

FIG. 4 is a diagram showing a structure of Embodiment Mode 2.

FIG. 5 is a diagram showing a structure of Embodiment Mode 3.

FIG. 6 is a diagram showing a structure of Embodiment Mode 4.

FIG. 7 is a diagram describing the structure of Embodiment Mode 2.

FIG. 8 is a chart describing the structure of Embodiment Mode 3.

FIG. 9 is a diagram showing a structure of Embodiment Mode 5.

FIG. 10 is a diagram showing a structure of Embodiment Mode 6.

DETAILED DESCRIPTION OF THE INVENTION

Although the present invention will be fully described by way ofembodiment modes with reference to the accompanying drawings, it is tobe understood that various changes and modifications will be apparent tothose skilled in the art. Therefore, unless such changes andmodifications depart from the scope of the present invention, theyshould be construed as being included therein. Note that throughout thedrawings, common reference numerals are used for common structures ofthe present invention described herein.

Embodiment Mode 1

In this embodiment mode, a structure of a wireless communication devicewhich performs the electric power charge and discharge system of thepresent invention is described below with reference to drawings.

FIG. 1 is a block diagram of the wireless communication device whichperforms the electric power charge and discharge system of the presentinvention. In FIG. 1, a wireless communication device 301 includes awireless driving portion 201 and a wireless charging portion 202. Thewireless driving portion 201 includes an antenna 101, an internalcircuit 102, a power supply switching circuit 103, a first battery 104,a charge controlling circuit 105, and a connector 106. The wirelesscharging portion 202 includes the antenna 101, a wireless chargecontrolling circuit 107, and a second battery 108.

The antenna 101 shown in FIG. 1 performs signal transmission andreception when the wireless communication device 301 performs wirelesscommunication, and corresponds to a system determined by its wirelesscommunication standard. As the antenna 101, a loop antenna, a dipoleantenna, a slot antenna, a monopole antenna, a notch antenna, a patchantenna, or the like can be used. The shape of the antenna may beselected in accordance with the system determined by the wirelesscommunication standard; in accordance with the wireless communicationstandard, an antenna with the optimal length and shape may be provided.

Note that as for the antenna 101 provided in the wireless communicationdevice 301 of the present invention, antennas with different shapes arecombined together for reception of electromagnetic waves in a pluralityof frequency bands may be applied. By providing antennas with differentshapes, a wireless communication device corresponding to a plurality ofwireless communication standards can be realized.

The internal circuit 102 shown in FIG. 1 demodulates a wirelesscommunication signal received by the antenna 101, and performs anoperation specified in the wireless communication device 301. Further,when signal transmission from the wireless communication device 301 isperformed as needed, a transmission signal is modulated and transmittedto the antenna 101 as a transmission signal. Electric power required foroperating the internal circuit 102 is supplied by either of the firstbattery 104 and the second battery 108 selected by the power supplyswitching circuit 103.

The first battery 104 shown in FIG. 1 is selected by the power supplyswitching circuit 103 to supply electric power as an operating powersupply of the internal circuit 102.

The charge controlling circuit 105 shown in FIG. 1 converts an AC signalsupplied from the connector 106 into a DC signal so as to be a voltagewhich can charge the first battery 104. As an example of the chargecontrolling circuit 105, a rectifier circuit, a constant voltagecircuit, a constant current circuit, and a diode are provided. Therectifier circuit mainly includes a diode and a smoothing capacitor. Therectifier circuit may be provided with a resistor or a capacitor inorder to adjust the impedance. The constant voltage circuit and theconstant current circuit convert a signal from the connector 106 to asignal for charging the first battery 104. The diode is provided inorder to prevent leaks of electric power from the first battery 104.

The connector 106 shown in FIG. 1 supplies electric power from anexternal power supply such as a fixed power supply through a cable.

The wireless charge controlling circuit 107 shown in FIG. 1 controls awireless electric power received by the antenna 101 to a voltage whichcan charge the second battery 108. As an example of the wireless chargecontrolling circuit 107, a rectifier circuit, a constant voltagecircuit, a boosting circuit, and a diode are provided. The rectifiercircuit mainly includes a diode and a smoothing capacitor. The rectifiercircuit may be provided with a resistor or a capacitor in order toadjust the impedance. The constant voltage circuit and the boostingcircuit perform conversion into a voltage for charging the secondbattery 108. The diode is provided in order to prevent leaks of electricpower from the battery.

Note that although the case where one wireless charge controllingcircuit 107 and one second battery 108 are provided in the wirelesscharging portion 202, other than the antenna 101 which is shared withthe wireless driving portion 201 is described in this embodiment mode,pluralities of the wireless charge controlling circuits 107 and thesecond batteries 108 may be provided as well. By providing pluralitiesof the wireless charge controlling circuits 107 and the second batteries108, charging capability of the wireless communication device 301 can beimproved.

Further, in the present invention, the first battery 104 and the secondbattery 108 refer to charging means which can restore a continuousoperating period of time by being charged. A secondary battery, acapacitor, and the like can be given as examples of the charging means,which are generically referred to as a battery in this specification. Abattery formed with a sheet shape is preferably used as the batteryalthough depending on an intended use. For example, reduction in size ispossible with the use of a lithium battery, preferably a lithium polymerbattery that uses a gel electrolyte, a lithium ion battery, or the like.Needless to say, any battery may be used as long as it can be charged,and a battery that can be charged and discharged, such as a nickel-metalhydride battery, a nickel cadmium battery, an organic radical battery, alead storage battery, an air secondary battery, a nickel zinc battery,or a silver zinc battery may be used. Alternatively, a high-capacitycapacitor or the like may be used.

It is to be noted that as a high-capacity capacitor that can be used aseach of the first battery 104 and the second battery 108 of the presentinvention, it is preferable to use a capacitor having large opposedareas of electrodes. It is preferable to use a double-layer electrolyticcapacitor formed using an electrode material having a large specificsurface area, such as activated carbon, fullerene, or a carbon nanotube.As compared with a battery, a capacitor has a simple structure and iseasily formed to be thin and stacked. A double-layer electrolyticcapacitor is preferable because it has a function of charging, does notdeteriorate much even if the frequencies of charging and discharging areincreased, and is excellent in rapid charging property.

The second battery 108 shown in FIG. 1 is selected by the power supplyswitching circuit 103 to supply electric power as an operating powersupply of the internal circuit 102. Note that description is madehereinafter under the following condition: the electric power storagecapacity of the second battery 108 is smaller than that of the firstbattery 104 and the electric power storage capacity is different in thefirst battery 104 and the second battery 108.

The electric power charge and discharge system of the present inventionis described using a flow chart of FIG. 2. Whether or not electric poweris being supplied from a fixed power supply through the connector 106 isjudged (STEP 401). In the case where electric power is being suppliedfrom the fixed power supply (followed by “YES” of STEP 401), theinternal circuit 102 is operated by using the electric power from thefixed power supply, and the first battery 104 is charged by electricpower transmitted from the connector 106 to the charge controllingcircuit 105. In addition, the second battery 108 is charged by anelectromagnetic wave supplied from the antenna (STEP 402).

In the case where electric power is not being supplied through the fixedpower supply in STEP 401 in FIG. 2 (followed by “NO” of STEP 401),whether or not the electric power capacitance of the second battery 108is enough to operate the internal circuit 102 is judged (STEP 403).Here, in the case where it is judged that the electric power capacitanceof the second battery 108 is enough to operate the internal circuit 102(followed by “YES” of STEP 403), the power supply switching circuit 103selects the second battery 108 as an electric power supply source to theinternal circuit 102 and operates the internal circuit 102 (STEP 404).In the case where it is judged that the electric power capacitance ofthe second battery 108 is not enough to operate the internal circuit 102(followed by “NO” of STEP 403), the power supply switching circuit 103selects the first battery 104 as an electric power supply source to theinternal circuit 102 and operates the internal circuit 102 (STEP 406).At STEP 406, the second battery 108 is charged by receiving anelectromagnetic wave with a wireless signal by an operation of thewireless charging portion 202. Note that when the internal circuit 102is operated by electric power supplying from the second battery 108 atSTEP 404, in the case where the electric power capacitance of the secondbattery 108 is short (followed by “YES” of STEP 405), STEP 406 follows.On the other hand, when the internal circuit 102 is operated by electricpower supplying from the second battery 108 at STEP 404, in the casewhere the electric power capacitance of the second battery 108 is enough(followed by “NO” of STEP 405), STEP 404 follows. Then, at the time whenthe electric power storage capacitance of the second battery 108 reachesenough electric power storage capacitance to operate the internalcircuit 102 by charging with electromagnetic waves existing in anexternal space, which are supplied from the antenna, charging iscompleted (STEP 407).

Based on the flow chart of FIG. 2 describing the electric power chargeand discharge system of the present invention, an advantage of thepresent invention is described with reference to FIGS. 3A to 3C. InFIGS. 3A to 3C, as one example, the electric power storage capacity ofthe first battery 104 is set to (100) and the electric power storagecapacity of the second battery 108 is set to (25) (see FIGS. 3A and 3B).Further, in FIGS. 3A to 3C, description is made under condition that aperiod of time for fully charging the electric power storage capacity ofthe second battery 108 is equal to a period of time for consuming (30)of the electric power storage capacity of the first battery 104.

The sum of electric power storage capacity of the first battery and thesecond battery shown in FIGS. 3A and 3B is only (125). According to theelectric power charge and discharge system of a wireless communicationdevice of the present invention in which charging and discharging areperformed in accordance to the flow chart of FIG. 2, discharging of thesecond battery, which is denoted by reference numeral 351, anddischarging of the first battery, which is denoted by reference numeral352, are performed alternately, and during the period in which the firstbattery is discharged, the second battery is charged, so that the sum ofelectric power storage capacity of the batteries is almost (200) (seeFIG. 3C). As described above, it is found that this embodiment modesufficiently resolves the problem of the short operating period of timeof a battery included in a wireless communication device.

As described above, by the electric power charge and discharge system ofthe present invention, improvement in hours of use of a battery can beachieved. Therefore, the frequency of carrying along an AC adapter forcharging the battery can be reduced.

Further, by the electric power charge and discharge system of thepresent invention, a battery can be charged noncontactly without using abattery charger. Therefore, an electronic device can be driven even inthe state where an AC adapter for charging the battery does not exist.

Embodiment Mode 2

In this embodiment mode, a structure of the wireless communicationdevice which performs the electric power charge and discharge system ofthe present invention described in Embodiment Mode 1, in which anantenna in a wireless charging portion is provided separately from anantenna in a wireless driving portion, is described below with referenceto drawings. Note that in the drawings used in this embodiment mode, thesame portions as Embodiment Mode 1 are denoted by the same referencenumerals in some cases.

FIG. 4 is a block diagram of the wireless communication device whichperforms the electric power charge and discharge system of the presentinvention. In FIG. 4, the wireless communication device 301 includes thewireless driving portion 201 and a wireless charging portion 203. Thewireless driving portion 201 includes the antenna 101, the internalcircuit 102, the power supply switching circuit 103, the first battery104, the charge controlling circuit 105, and the connector 106. Thewireless charging portion 203 includes the wireless charge controllingcircuit 107, the second battery 108, and a wireless charging antenna109.

The antenna 101 shown in FIG. 4 performs signal transmission andreception when the wireless communication device 301 performs wirelesscommunication, and corresponds to a system determined by its wirelesscommunication standard. As the antenna 101, a loop antenna, a dipoleantenna, a slot antenna, a monopole antenna, a notch antenna, a patchantenna, or the like can be used. The shape of the antenna may beselected in accordance with the system determined by the wirelesscommunication standard; in accordance with the wireless communicationstandard, an antenna with the optimal length and shape may be provided.

The internal circuit 102 shown in FIG. 4 demodulates a wirelesscommunication signal received by the antenna 101, and performs anoperation specified in the wireless communication device 301. Further,when signal transmission from the wireless communication device 301 isperformed as needed, a transmission signal is modulated and transmittedto the antenna 101 as a transmission signal. Electric power required foroperating the internal circuit 102 is supplied by either of the firstbattery 104 and the second battery 108 selected by the power supplyswitching circuit 103.

The first battery 104 shown in FIG. 4 is selected by the power supplyswitching circuit 103 to supply electric power as an operating powersupply of the internal circuit 102.

The charge controlling circuit 105 shown in FIG. 4 converts an AC signalsupplied from the connector 106 into a DC signal so as to be a voltagewhich can charge the first battery 104. As an example of the chargecontrolling circuit 105, a rectifier circuit, a constant voltagecircuit, a constant current circuit, and a diode are provided. Therectifier circuit mainly includes a diode and a smoothing capacitor. Therectifier circuit may be provided with a resistor or a capacitor inorder to adjust the impedance. The constant voltage circuit and theconstant current circuit convert a signal from the connector 106 to asignal for charging the first battery 104. The diode is provided inorder to prevent leaks of electric power from the first battery 104.

Note that although the case where one wireless charge controllingcircuit 107 and one second battery 108 are provided in the wirelesscharging portion 203 is described in this embodiment mode, pluralitiesof the wireless charge controlling circuits 107 and the second batteries108 may be provided as well. By providing pluralities of the wirelesscharge controlling circuits 107 and the second batteries 108, chargingcapability of the wireless communication device 301 can be improved.

Further, in the present invention, the first battery 104 and the secondbattery 108 refer to charging means which can restore a continuousoperating period of time by being charged. A secondary battery, acapacitor, and the like can be given as examples of the charging means,which are generically referred to as a battery in this specification. Abattery formed with a sheet shape is preferably used as the batteryalthough depending on an intended use. For example, reduction in size ispossible with the use of a lithium battery, preferably a lithium polymerbattery that uses a gel electrolyte, a lithium ion battery, or the like.Needless to say, any battery may be used as long as it can be charged,and a battery that can be charged and discharged, such as a nickel-metalhydride battery, a nickel cadmium battery, an organic radical battery, alead storage battery, an air secondary battery, a nickel zinc battery,or a silver zinc battery may be used. Alternatively, a high-capacitycapacitor or the like may be used.

It is to be noted that as a high-capacity capacitor that can be used aseach of the first battery 104 and the second battery 108 of the presentinvention, it is preferable to use a capacitor having large opposedareas of electrodes. It is preferable to use a double-layer electrolyticcapacitor formed using an electrode material having a large specificsurface area, such as activated carbon, fullerene, or a carbon nanotube.As compared with a battery, a capacitor has a simple structure and iseasily formed to be thin and stacked. A double-layer electrolyticcapacitor is preferable because it has a function of charging, does notdeteriorate much even if the frequencies of charging and discharging areincreased, and is excellent in rapid charging property.

The connector 106 shown in FIG. 4 supplies electric power from a fixedpower supply such as a household power supply through a cable.

The wireless charge controlling circuit 107 shown in FIG. 4 controls anelectromagnetic wave received by the wireless charging antenna 109 to avoltage which can charge the second battery 108. As an example of thewireless charge controlling circuit 107, a rectifier circuit, a constantvoltage circuit, a boosting circuit, and a diode are provided. Therectifier circuit mainly includes a diode and a smoothing capacitor. Therectifier circuit may be provided with a resistor or a capacitor inorder to adjust the impedance. The constant voltage circuit and theboosting circuit perform conversion into a voltage for charging thesecond battery 108. The diode is provided in order to prevent leaks ofelectric power from the battery.

The second battery 108 shown in FIG. 4 is selected by the power supplyswitching circuit 103 to supply electric power as an operating powersupply of the internal circuit 102. Note that description is madehereinafter under the following condition: the electric power storagecapacity of the second battery 108 is smaller than that of the firstbattery 104 and the electric power storage capacity is different in thefirst battery 104 and the second battery 108.

The wireless charging antenna 109 shown in FIG. 4 is an antenna only forcharging the second battery 108, and it is not necessarily an antennacorresponding to a standard of the wireless communication device 301 andis not necessarily the same as the antenna 101. As the wireless chargingantenna 109, a loop antenna, a dipole antenna, a slot antenna, amonopole antenna, a notch antenna, a patch antenna, or the like can beused. The shape of the antenna may be selected in accordance with thesystem determined by the wireless communication standard; in accordancewith the wireless communication standard, an antenna with the optimallength and shape may be provided.

Note that as for the wireless charging antenna 109 provided in thewireless communication device 301 of the present invention, antennaswith different shapes are combined together for reception ofelectromagnetic waves in a plurality of frequency bands may be applied.By providing antennas with different shapes, a wireless communicationdevice corresponding to a plurality of wireless communication standardscan be realized.

The present invention described in this embodiment mode can be operatedin accordance with the flow chart of FIG. 2 as described in EmbodimentMode 1. Therefore, the problem of the short operating period of time ofa battery included in a wireless communication device can be resolved.

Further, in this embodiment mode, the wireless charging antenna 109 isprovided and the efficiency of receiving electric power by receiving anelectromagnetic wave with the use of the wireless charging antenna 109is high compared to the antenna 101 described in Embodiment Mode 1, sothat the battery can be further saved. An example thereof is shown inFIG. 7.

In FIG. 7, since the efficiency of receiving electric power by receivingan electromagnetic wave is higher than that of the example of FIG. 3described in Embodiment Mode 1, a period of time required for chargingall the capacity of the second battery 108 can be reduced. As anexample, in FIG. 7, description is made under condition that a period oftime for charging all of the electric power storage capacity of thesecond battery 108 is equal to a period of time for using (20) of theelectric power storage capacity of the first battery 104. In the exampleof FIGS. 3A to 3C described in Embodiment Mode 1, the sum of electricpower storage capacity of the first battery and the second battery isalmost (200). In this embodiment mode, as shown in FIG. 7, sincecharging and discharging are performed in accordance to the flow chartof FIG. 2, the discharging 351 of the second battery and the discharging352 of the first battery are performed alternately, and during theperiod in which the first battery is discharged, the second battery ischarged, so that the sum of electric power storage capacity of thebatteries can be almost (225). That is, by using the wireless chargingantenna 109 having higher efficiency of receiving electric wave than theantenna 101, a more advantageous effect can be produced in resolving theproblem of the short operating period of time.

As described above, by the electric power charge and discharge system ofthe present invention, improvement of hours of use of a battery can beachieved. Therefore, the frequency of carrying along an AC adapter forcharging the battery can be reduced.

Further, by the electric power charge and discharge system of thepresent invention, a battery can be charged noncontactly without using abattery charger. Therefore, an electronic device can be driven even inthe state where an AC adapter for charging the battery does not exist.

Note that this embodiment mode can be implemented in combination withany of the other embodiment modes in this specification.

Embodiment Mode 3

In this embodiment mode, a structure of the wireless communicationdevice which performs the electric power charge and discharge system ofthe present invention described in Embodiment Mode 1, in which a chargeswitching circuit is provided in a wireless charging portion, isdescribed below with reference to drawings. Note that in the drawingsused in this embodiment mode, the same portions as Embodiment Mode 1 aredenoted by the same reference numerals in some cases.

FIG. 5 is a block diagram of the wireless communication device whichperforms the electric power charge and discharge system of the presentinvention. In FIG. 5, the wireless communication device 301 includes thewireless driving portion 201 and a wireless charging portion 204. Thewireless driving portion 201 includes the antenna 101, the internalcircuit 102, the power supply switching circuit 103, the first battery104, the charge controlling circuit 105, and the connector 106. Thewireless charging portion 204 includes the antenna 101, the wirelesscharge controlling circuit 107, the second battery 108, and a chargeswitching circuit 110.

The antenna 101 shown in FIG. 5 performs signal transmission andreception when the wireless communication device 301 performs wirelesscommunication, and corresponds to a system determined by its wirelesscommunication standard. As the antenna 101, a loop antenna, a dipoleantenna, a slot antenna, a monopole antenna, a notch antenna, a patchantenna, or the like can be used. The shape of the antenna may beselected in accordance with the system determined by the wirelesscommunication standard; in accordance with the wireless communicationstandard, an antenna with the optimal length and shape may be provided.

The internal circuit 102 shown in FIG. 5 demodulates a wirelesscommunication signal received by the antenna 101, and performs anoperation specified in the wireless communication device 301. Further,when signal transmission from the wireless communication device 301 isperformed as needed, a transmission signal is modulated and transmittedto the antenna 101 as a transmission signal. Electric power required foroperating the internal circuit 102 is supplied by either of the firstbattery 104 and the second battery 108 selected by the power supplyswitching circuit 103.

The first battery 104 shown in FIG. 5 is selected by the power supplyswitching circuit 103 to supply electric power as an operating powersupply of the internal circuit 102.

The charge controlling circuit 105 shown in FIG. 5 converts an AC signalsupplied from the connector 106 into a DC signal so as to be a voltagewhich can charge the first battery 104. As an example of the chargecontrolling circuit 105, a rectifier circuit, a constant voltagecircuit, a constant current circuit, and a diode are provided. Therectifier circuit mainly includes a diode and a smoothing capacitor. Therectifier circuit may be provided with a resistor or a capacitor inorder to adjust the impedance. The constant voltage circuit and theconstant current circuit convert a signal from the connector 106 to asignal for charging the first battery 104. The diode is provided inorder to prevent leaks of electric power from the first battery.

Note that although the case where one wireless charge controllingcircuit 107 and one second battery 108 are provided in the wirelesscharging portion 203, other than the antenna 101 which is shared withthe wireless driving portion 201 is described in this embodiment mode,pluralities of the wireless charge controlling circuits 107 and thesecond batteries 108 may be provided as well. By providing pluralitiesof the wireless charge controlling circuits 107 and the second batteries108, charging capability of the wireless communication device 301 can beimproved.

Further, in the present invention, the first battery 104 and the secondbattery 108 refer to charging means which can restore a continuousoperating period of time by being charged. A secondary battery, acapacitor, and the like can be given as examples of the charging means,which are generically referred to as a battery in this specification. Abattery formed with a sheet shape is preferably used as the batteryalthough depending on an intended use. For example, reduction in size ispossible with the use of a lithium battery, preferably a lithium polymerbattery that uses a gel electrolyte, a lithium ion battery, or the like.Needless to say, any battery may be used as long as it can be charged,and a battery that can be charged and discharged, such as a nickel-metalhydride battery, a nickel cadmium battery, an organic radical battery, alead storage battery, an air secondary battery, a nickel zinc battery,or a silver zinc battery may be used. Alternatively, a high-capacitycapacitor or the like may be used.

It is to be noted that as a high-capacity capacitor that can be used aseach of the first battery 104 and the second battery 108 of the presentinvention, it is preferable to use a capacitor having large opposedareas of electrodes. It is preferable to use a double-layer electrolyticcapacitor formed using an electrode material having a large specificsurface area, such as activated carbon, fullerene, or a carbon nanotube.As compared with a battery, a capacitor has a simple structure and iseasily formed to be thin and stacked. A double-layer electrolyticcapacitor is preferable because it has a function of charging, does notdeteriorate much even if the frequencies of charging and discharging areincreased, and is excellent in rapid charging property.

The charge switching circuit 110 is a circuit to switch electric powersupplied to the second battery 108 from electric power of the wirelesscharge controlling circuit 107 to electric power of the chargecontrolling circuit 105 when a voltage of a fixed power supply isinputted to the connector 106 and electric power is supplied from thecharge controlling circuit 105. Electric power supplied from thewireless charge controlling circuit 107 to the second battery 108 isfaint as compared to electric power inputted through the fixed powersupply. Therefore, during a period in which current can be supplied fromthe fixed power supply, it is efficient that electric power to thesecond battery 108 is also supplied from the charge controlling circuit105. When the charge controlling circuit 105 does not supply electricpower, that is, when electric power supply from the fixed power supplyto the connector 106 is stopped, electric power from the wireless chargecontrolling circuit is supplied again to the second battery 108.

The connector 106 shown in FIG. 5 supplies electric power from the fixedpower supply through a cable.

The wireless charge controlling circuit 107 shown in FIG. 5 controls anelectromagnetic wave received by the antenna 101 to a voltage which cancharge the second battery 108. As an example of the wireless chargecontrolling circuit 107, a rectifier circuit, a constant voltagecircuit, a boosting circuit, and a diode are provided. The rectifiercircuit mainly includes a diode and a smoothing capacitor. The rectifiercircuit may be provided with a resistor or a capacitor in order toadjust the impedance. The constant voltage circuit and the boostingcircuit perform conversion into a voltage for charging the secondbattery 108. The diode is provided in order to prevent leaks of electricpower from the battery.

The second battery 108 shown in FIG. 5 is selected by the power supplyswitching circuit 103 to supply electric power as an operating powersupply of the internal circuit 102. Note that description is madehereinafter under the following condition: the electric power storagecapacity of the second battery 108 is smaller than that of the firstbattery 104 and the electric power storage capacity is different in thefirst battery 104 and the second battery 108.

An operation example of this embodiment mode is described using a flowchart of FIG. 8. Whether or not electric power is being supplied fromthe fixed power supply through the connector 106 is judged (STEP 501).In the case where electric power is being supplied from the fixed powersupply (followed by “YES” of STEP 501), the internal circuit 102 isoperated by using the electric power from the fixed power supply, andthe first battery 104 is charged by electric power transmitted from theconnector 106 to the charge controlling circuit 105. In addition, anelectric power supply source to the second battery 108 is changed fromthe wireless charge controlling circuit 107 to the charge controllingcircuit 105 by the charge switching circuit 110 and charging isperformed (STEP 502).

In the case where electric power is not being supplied through the fixedpower supply in STEP 501 in FIG. 8 (followed by “NO” of STEP 501),whether or not the electric power capacitance of the second battery 108is enough to operate the internal circuit 102 is judged (STEP 503).Here, in the case where it is judged that the electric power capacitanceof the second battery 108 is enough to operate the internal circuit 102(followed by “YES” of STEP 503), the power supply switching circuit 103selects the second battery 108 as an electric power supply source to theinternal circuit 102 and operates the internal circuit 102 (STEP 504).In the case where it is judged that the electric power capacitance ofthe second battery 108 is not enough to operate the internal circuit 102(followed by “NO” of STEP 503), the power supply switching circuit 103selects the first battery 104 as an electric power supply source to theinternal circuit 102 and operates the internal circuit 102 (STEP 506).At STEP 506, the second battery 108 is charged by receiving anelectromagnetic wave with a wireless signal by an operation of thewireless charging portion 202. Note that when the internal circuit 102is operated by electric power supplying from the second battery 108 atSTEP 504, in the case where the electric power capacitance of the secondbattery 108 is low (followed by “YES” of STEP 505), STEP 506 follows. Onthe other hand, when the internal circuit 102 is operated by electricpower supplying from the second battery 108 at STEP 504, in the casewhere the electric power capacitance of the second battery 108 is enough(followed by “NO” of STEP 505), STEP 504 follows. Then, at the time whenthe electric power storage capacitance of the second battery 108 reachesenough electric power storage capacitance to operate the internalcircuit 102 by charging with electromagnetic waves existing in anexternal space, which are supplied from the antenna, charging iscompleted (STEP 507).

As described above, by the electric power charge and discharge system ofthe present invention, improvement in hours of use of a battery can beachieved. Therefore, the frequency of carrying along an AC adapter forcharging the battery can be reduced.

Further, by the electric power charge and discharge system of thepresent invention, a battery can be charged noncontactly without using abattery charger. Therefore, an electronic device can be driven even inthe state where an AC adapter for charging the battery does not exist.

Note that this embodiment mode can be implemented in combination withany of the other embodiment modes in this specification.

Embodiment Mode 4

In this embodiment mode, a structure of the wireless communicationdevice which performs the electric power charge and discharge system ofthe present invention described in Embodiment Mode 2, in which a chargeswitching circuit is provided in a wireless charging portion, isdescribed below with reference to drawings. Note that in the drawingsused in this embodiment mode, the same portions as Embodiment Mode 2 aredenoted by the same reference numerals in some cases.

FIG. 6 is a block diagram of the wireless communication device whichperforms the electric power charge and discharge system of the presentinvention. In FIG. 6, the wireless communication device 301 includes thewireless driving portion 201 and a wireless charging portion 205. Thewireless driving portion 201 includes the antenna 101, the internalcircuit 102, the power supply switching circuit 103, the first battery104, the charge controlling circuit 105, and the connector 106. Thewireless charging portion 205 includes the wireless charge controllingcircuit 107, the second battery 108, the wireless charging antenna 109,and the charge switching circuit 110.

The antenna 101 shown in FIG. 6 performs signal transmission andreception when the wireless communication device 301 performs wirelesscommunication, and corresponds to a system determined by its wirelesscommunication standard. As the antenna 101, a loop antenna, a dipoleantenna, a slot antenna, a monopole antenna, a notch antenna, a patchantenna, or the like can be used. The shape of the antenna may beselected in accordance with the system determined by the wirelesscommunication standard; in accordance with the wireless communicationstandard, an antenna with the optimal length and shape may be provided.

The internal circuit 102 shown in FIG. 6 demodulates a wirelesscommunication signal received by the antenna 101, and performs anoperation specified in the wireless communication device 301. Further,when signal transmission from the wireless communication device 301 isperformed as needed, a transmission signal is modulated and transmittedto the antenna 101 as a transmission signal. Electric power required foroperating the internal circuit 102 is supplied by either of the firstbattery 104 and the second battery 108 selected by the power supplyswitching circuit 103.

The first battery 104 shown in FIG. 6 is selected by the power supplyswitching circuit 103 to supply electric power as an operating powersupply of the internal circuit 102.

The charge controlling circuit 105 shown in FIG. 6 converts an AC signalsupplied from the connector 106 into a DC signal so as to be a voltagewhich can charge the first battery 104. As an example of the chargecontrolling circuit 105, a rectifier circuit, a constant voltagecircuit, a constant current circuit, and a diode are provided. Therectifier circuit mainly includes a diode and a smoothing capacitor. Therectifier circuit may be provided with a resistor or a capacitor inorder to adjust the impedance. The constant voltage circuit and theconstant current circuit convert a signal from the connector 106 to asignal for charging the first battery 104. The diode is provided inorder to prevent leaks of electric power from the first battery.

Note that although the case where one wireless charge controllingcircuit 107 and one second battery 108 are provided in the wirelesscharging portion 205 is described in this embodiment mode, pluralitiesof the wireless charge controlling circuits 107 and the second batteries108 may be provided as well. By providing pluralities of the wirelesscharge controlling circuits 107 and the second batteries 108, chargingcapability of the wireless communication device 301 can be improved.

Further, in the present invention, the first battery 104 and the secondbattery 108 refer to charging means which can restore a continuousoperating period of time by being charged. A secondary battery, acapacitor, and the like can be given as examples of the charging means,which are generically referred to as a battery in this specification. Abattery formed with a sheet shape is preferably used as the batteryalthough depending on an intended use. For example, reduction in size ispossible with the use of a lithium battery, preferably a lithium polymerbattery that uses a gel electrolyte, a lithium ion battery, or the like.Needless to say, any battery may be used as long as it can be charged,and a battery that can be charged and discharged, such as a nickel-metalhydride battery, a nickel cadmium battery, an organic radical battery, alead storage battery, an air secondary battery, a nickel zinc battery,or a silver zinc battery may be used. Alternatively, a high-capacitycapacitor or the like may be used.

It is to be noted that as a high-capacity capacitor that can be used aseach of the first battery 104 and the second battery 108 of the presentinvention, it is preferable to use a capacitor having large opposedareas of electrodes. It is preferable to use a double-layer electrolyticcapacitor formed using an electrode material having a large specificsurface area, such as activated carbon, fullerene, or a carbon nanotube.As compared with a battery, a capacitor has a simple structure and iseasily formed to be thin and stacked. A double-layer electrolyticcapacitor is preferable because it has a function of charging, does notdeteriorate much even if the frequencies of charging and discharging areincreased, and is excellent in rapid charging property.

The charge switching circuit 110 is a circuit to switch electric powersupplied to the second battery 108 from electric power of the wirelesscharge controlling circuit 107 to electric power of the chargecontrolling circuit 105 when a voltage of a fixed power supply isinputted to the connector 106 and electric power is supplied from thecharge controlling circuit 105. Electric power supplied from thewireless charge controlling circuit 107 to the second battery 108 isfaint as compared to electric power inputted through the fixed powersupply. Therefore, during a period in which current can be supplied fromthe fixed power supply, it is efficient that electric power to thesecond battery 108 is also supplied from the charge controlling circuit105. When the charge controlling circuit 105 does not supply electricpower, that is, when electric power supply from the fixed power supplyto the connector 106 is stopped, electric power from the wireless chargecontrolling circuit is supplied again to the second battery 108.

The connector 106 shown in FIG. 6 supplies electric power from the fixedpower supply through a cable.

The wireless charge controlling circuit 107 shown in FIG. 6 controls anelectromagnetic wave received by the wireless charging antenna 109 to avoltage which can charge the second battery 108. As an example of thewireless charge controlling circuit 107, a rectifier circuit, a constantvoltage circuit, a boosting circuit, and a diode are provided. Therectifier circuit mainly includes a diode and a smoothing capacitor. Therectifier circuit may be provided with a resistor or a capacitor inorder to adjust the impedance. The constant voltage circuit and theboosting circuit perform conversion into a voltage for charging thesecond battery 108. The diode is provided in order to prevent leaks ofelectric power from the battery.

The second battery 108 shown in FIG. 6 is selected by the power supplyswitching circuit 103 to supply electric power as an operating powersupply of the internal circuit 102. Note that description is madehereinafter under the following condition: the electric power storagecapacity of the second battery 108 is smaller than that of the firstbattery 104 and the electric power storage capacity is different in thefirst battery 104 and the second battery 108.

The wireless charging antenna 109 shown in FIG. 6 is an antenna only forcharging the second battery 108, and it is not necessarily an antennacorresponding to a standard of the wireless communication device 301 andis not necessarily the same as the antenna 101. As the wireless chargingantenna 109, a loop antenna, a dipole antenna, a slot antenna, amonopole antenna, a notch antenna, a patch antenna, or the like can beused. The shape of the antenna may be selected in accordance with thesystem determined by the wireless communication standard; in accordancewith the wireless communication standard, an antenna with the optimallength and shape may be provided.

The present invention described in this embodiment mode can be operatedin accordance with the flow chart of FIG. 8 as described in EmbodimentMode 3. Therefore, the problem of the short operating period of time ofa battery included in a wireless communication device can be resolved.Further, since the wireless charging antenna 109 is provided, as shownin FIG. 7 of Embodiment Mode 2, a more advantageous effect can beproduced in resolving the problem of the short operating period of time.

As described above, by the electric power charge and discharge system ofthe present invention, improvement in hours of use of a battery can beachieved. Therefore, the frequency of carrying along an AC adapter forcharging the battery can be reduced.

Further, by the electric power charge and discharge system of thepresent invention, a battery can be charged noncontactly without using abattery charger. Therefore, an electronic device can be driven even inthe state where an AC adapter for charging the battery does not exist.

Note that this embodiment mode can be implemented in combination withany of the other embodiment modes in this specification.

Embodiment Mode 5

In this embodiment mode, a structure of the wireless communicationdevice which performs the electric power charge and discharge system ofthe present invention described in Embodiment Mode 1, in which anexternal antenna is provided and wireless communication can be performedby connecting the external antenna to a communication antenna, isdescribed below with reference to drawings. Note that in the drawingsused in this embodiment mode, the same portions as Embodiment Mode 1 aredenoted by the same reference numerals in some cases.

FIG. 9 is a block diagram of the wireless communication device whichperforms the electric power charge and discharge system of the presentinvention. In FIG. 9, an electrical device 302 can perform wirelesscommunication by connection between an external antenna 112 and acommunication connector 111. The electrical device 302 can also operatealone even in the state where wireless communication is not performed,that is, when the external antenna 112 is not connected to thecommunication connector 111. In FIG. 9, the electrical device 302includes a wireless driving portion 211 and a wireless charging portion206. The wireless driving portion 211 includes the internal circuit 102,the power supply switching circuit 103, the first battery 104, thecharge controlling circuit 105, and the connector 106. The wirelesscharging portion 206 includes the communication connector 111, thewireless charge controlling circuit 107, and the second battery 108.

The internal circuit 102 shown in FIG. 9 is supplied with electric powerfrom the battery selected from the first battery 104 and the secondbattery 108 by the power supply switching circuit 103 to operate.Further, only in the case of performing wireless communication,transmission and reception of wireless communication signals areperformed with the external antenna 112 through the communicationconnector 111.

The first battery 104 shown in FIG. 9 is selected by the power supplyswitching circuit 103 to supply electric power as an operating powersupply of the internal circuit 102.

The charge controlling circuit 105 shown in FIG. 9 converts an AC signalsupplied from the connector 106 into a DC signal so as to be a voltagewhich can charge the first battery 104. As an example of the chargecontrolling circuit 105, a rectifier circuit, a constant voltagecircuit, a constant current circuit, and a diode are provided. Therectifier circuit mainly includes a diode and a smoothing capacitor. Therectifier circuit may be provided with a resistor or a capacitor inorder to adjust the impedance. The constant voltage circuit and theconstant current circuit convert a signal from the connector 106 to asignal for charging the first battery 104. The diode is provided inorder to prevent leaks of electric power from the first battery.

Further, in the present invention, the first battery 104 and the secondbattery 108 refer to charging means which can restore a continuousoperating period of time by being charged. A secondary battery, acapacitor, and the like can be given as examples of the charging means,which are generically referred to as a battery in this specification. Abattery formed with a sheet shape is preferably used as the batteryalthough depending on an intended use. For example, reduction in size ispossible with the use of a lithium battery, preferably a lithium polymerbattery that uses a gel electrolyte, a lithium ion battery, or the like.Needless to say, any battery may be used as long as it can be charged,and a battery that can be charged and discharged, such as a nickel-metalhydride battery, a nickel cadmium battery, an organic radical battery, alead storage battery, an air secondary battery, a nickel zinc battery,or a silver zinc battery may be used. Alternatively, a high-capacitycapacitor or the like may be used.

It is to be noted that as a high-capacity capacitor that can be used aseach of the first battery 104 and the second battery 108 of the presentinvention, it is preferable to use a capacitor having large opposedareas of electrodes. It is preferable to use a double-layer electrolyticcapacitor formed using an electrode material having a large specificsurface area, such as activated carbon, fullerene, or a carbon nanotube.As compared with a battery, a capacitor has a simple structure and iseasily formed to be thin and stacked. A double-layer electrolyticcapacitor is preferable because it has a function of charging, does notdeteriorate much even if the frequencies of charging and discharging areincreased, and is excellent in rapid charging property.

The connector 106 shown in FIG. 9 supplies electric power from a fixedpower supply through a cable.

The wireless charge controlling circuit 107 shown in FIG. 9 controls anelectromagnetic wave received by the external antenna 112 to a voltagewhich can charge the second battery 108 in the case where the externalantenna 112 is connected to the communication connector 111. As anexample of the wireless charge controlling circuit 107, a rectifiercircuit, a constant voltage circuit, a boosting circuit, and a diode areprovided. The rectifier circuit mainly includes a diode and a smoothingcapacitor. The rectifier circuit may be provided with a resistor or acapacitor in order to adjust the impedance. The constant voltage circuitand the boosting circuit perform conversion into a voltage for chargingthe second battery 108. The diode is provided in order to prevent leaksof electric power from the battery.

The second battery 108 shown in FIG. 9 is selected by the power supplyswitching circuit 103 to supply electric power as an operating powersupply of the internal circuit 102. Note that description is madehereinafter under the following condition: the electric power storagecapacity of the second battery 108 is smaller than that of the firstbattery 104 and the electric power storage capacity is different in thefirst battery 104 and the second battery 108.

The present invention described in this embodiment mode can be operatedin accordance with the flow chart of FIG. 2 as described in EmbodimentMode 1. Therefore, the problem of the short operating period of time ofa battery included in a wireless communication device can be resolved.

As described above, by the electric power charge and discharge system ofthe present invention, improvement in hours of use of a battery can beachieved. Therefore, the frequency of carrying along an AC adapter forcharging the battery can be reduced.

Further, by the electric power charge and discharge system of thepresent invention, a battery can be charged noncontactly without using abattery charger. Therefore, an electronic device can be driven even inthe state where an AC adapter for charging the battery does not exist.

Note that this embodiment mode can be implemented in combination withany of the other embodiment modes in this specification.

Embodiment Mode 6

In this embodiment mode, a structure of the wireless communicationdevice which performs the electric power charge and discharge system ofthe present invention described in Embodiment Mode 2, in which a chargeswitching circuit is provided in a wireless charging portion, isdescribed below with reference to drawings. Note that in the drawingsused in this embodiment mode, the same portions as Embodiment Mode 2 aredenoted by the same reference numerals in some cases.

FIG. 10 is a block diagram of the wireless communication device whichperforms the electric power charge and discharge system of the presentinvention. In FIG. 10, the electrical device 302 can perform wirelesscommunication by connection between the external antenna 112 and thecommunication connector 111. The electrical device 302 can also operatealone even in the state where wireless communication is not performed,that is, when the external antenna 112 is not connected to thecommunication connector 111. In FIG. 10, the electrical device 302includes the wireless driving portion 211 and a wireless chargingportion 207. The wireless driving portion 211 includes the internalcircuit 102, the power supply switching circuit 103, the first battery104, the charge controlling circuit 105, and the connector 106. Thewireless charging portion 207 includes the communication connector 111,the wireless charge controlling circuit 107, the second battery 108, andthe charge switching circuit 110.

The internal circuit 102 shown in FIG. 10 is supplied with electricpower from the battery selected from the first battery 104 and thesecond battery 108 by the power supply switching circuit 103 to operate.Further, only in the case of performing wireless communication,transmission and reception of wireless communication signals areperformed with the external antenna 112 through the communicationconnector 111.

The first battery 104 shown in FIG. 10 is selected by the power supplyswitching circuit 103 to supply electric power as an operating powersupply of the internal circuit 102.

The charge controlling circuit 105 shown in FIG. 10 converts an ACsignal supplied from the connector 106 into a DC signal so as to be avoltage which can charge the first battery 104. As an example of thecharge controlling circuit 105, a rectifier circuit, a constant voltagecircuit, a constant current circuit, and a diode are provided. Therectifier circuit mainly includes a diode and a smoothing capacitor. Therectifier circuit may be provided with a resistor or a capacitor inorder to adjust the impedance. The constant voltage circuit and theconstant current circuit convert a signal from the connector 106 to asignal for charging the first battery 104. The diode is provided inorder to prevent leaks of electric power from the first battery.

Further, in the present invention, the first battery 104 and the secondbattery 108 refer to charging means which can restore a continuousoperating period of time by being charged. A secondary battery, acapacitor, and the like can be given as examples of the charging means,which are generically referred to as a battery in this specification. Abattery formed with a sheet shape is preferably used as the batteryalthough depending on an intended use. For example, reduction in size ispossible with the use of a lithium battery, preferably a lithium polymerbattery that uses a gel electrolyte, a lithium ion battery, or the like.Needless to say, any battery may be used as long as it can be charged,and a battery that can be charged and discharged, such as a nickel-metalhydride battery, a nickel cadmium battery, an organic radical battery, alead storage battery, an air secondary battery, a nickel zinc battery,or a silver zinc battery may be used. Alternatively, a high-capacitycapacitor or the like may be used.

It is to be noted that as a high-capacity capacitor that can be used aseach of the first battery 104 and the second battery 108 of the presentinvention, it is preferable to use a capacitor having large opposedareas of electrodes. It is preferable to use a double-layer electrolyticcapacitor formed using an electrode material having a large specificsurface area, such as activated carbon, fullerene, or a carbon nanotube.As compared with a battery, a capacitor has a simple structure and iseasily formed to be thin and stacked. A double-layer electrolyticcapacitor is preferable because it has a function of charging, does notdeteriorate much even if the frequencies of charging and discharging areincreased, and is excellent in rapid charging property.

The connector 106 shown in FIG. 10 supplies electric power from a fixedpower supply through a cable.

The wireless charge controlling circuit 107 shown in FIG. 10 controls anelectromagnetic wave received by the external antenna 112 to a voltagewhich can charge the second battery 108 in the case where the externalantenna 112 is connected to the communication connector 111. As anexample of the wireless charge controlling circuit 107, a rectifiercircuit, a constant voltage circuit, a boosting circuit, and a diode areprovided. The rectifier circuit mainly includes a diode and a smoothingcapacitor. The rectifier circuit may be provided with a resistor or acapacitor in order to adjust the impedance. The constant voltage circuitand the boosting circuit perform conversion into a voltage for chargingthe second battery 108. The diode is provided in order to prevent leaksof electric power from the battery.

The second battery 108 shown in FIG. 10 is selected by the power supplyswitching circuit 103 to supply electric power as an operating powersupply of the internal circuit 102. Note that description is madehereinafter under the following condition: the electric power storagecapacity of the second battery 108 is smaller than that of the firstbattery 104 and the electric power storage capacity is different in thefirst battery 104 and the second battery 108.

The charge switching circuit 110 is a circuit to switch electric powersupplied to the second battery 108 from electric power of the wirelesscharge controlling circuit 107 to electric power of the chargecontrolling circuit 105 when a voltage of a fixed power supply isinputted to the connector 106 and electric power is supplied from thecharge controlling circuit 105. Electric power supplied from thewireless charge controlling circuit 107 to the second battery 108 isfaint as compared to electric power inputted through the fixed powersupply. Therefore, during a period in which current can be supplied fromthe fixed power supply, it is efficient that electric power to thesecond battery 108 is also supplied from the charge controlling circuit105. When the charge controlling circuit 105 does not supply electricpower, that is, when electric power supply from the fixed power supplyto the connector 106 is stopped, electric power from the wireless chargecontrolling circuit is supplied again to the second battery 108.

The present invention described in this embodiment mode can be operatedin accordance with the flow chart of FIG. 8 as described in EmbodimentMode 3. Therefore, the problem of the short operating period of time ofa battery included in a wireless communication device can be resolved.

As described above, by the electric power charge and discharge system ofthe present invention, improvement in hours of use of a battery can beachieved. Therefore, the frequency of carrying along an AC adapter forcharging the battery can be reduced.

Further, by the electric power charge and discharge system of thepresent invention, a battery can be charged noncontactly without using abattery charger. Therefore, an electronic device can be driven even inthe state where an AC adapter for charging the battery does not exist.

Note that this embodiment mode can be implemented in combination withany of the other embodiment modes in this specification.

This application is based on Japanese Patent Application Serial No.2006296964 filed in Japan Patent Office on Oct. 31, 2006, the entirecontents of which are hereby incorporated by reference.

What is claimed is:
 1. A wireless communication device comprising: anelectrical device comprising: a connector; a battery electricallyconnected to the connector; and an inner circuit electrically connectedto the battery; and an antenna connectable to the connector, wherein theantenna is attachable to and detachable from the electrical device,wherein the battery is configured to be charged by electric power fromthe antenna.
 2. The wireless communication device according to claim 1,wherein the connector is a communication connector electricallyconnected to the inner circuit.
 3. The wireless communication deviceaccording to claim 1, wherein the electrical device further comprises awireless charge controlling circuit electrically connected to thebattery and the connector.
 4. The wireless communication deviceaccording to claim 3, wherein the wireless charge controlling circuit isconfigured to transform an electromagnetic wave received by the antennainto voltage capable of charging the battery.
 5. The wirelesscommunication device according to claim 3, wherein the wireless chargecontrolling circuit comprises a rectifier circuit, a constant voltagecircuit, a booster circuit, and a diode.
 6. The wireless communicationdevice according to claim 1, wherein the battery is a lithium ionbattery.
 7. The wireless communication device according to claim 1,wherein the battery is a double-layer electrolytic capacitor.
 8. Awireless communication device comprising: an electrical devicecomprising: a first connector; a second connector; a batteryelectrically connected to the first connector and the second connector;and an inner circuit electrically connected to the battery; and anantenna connectable to the first connector, wherein the antenna isattachable to and detachable from the electrical device, wherein thebattery is configured to be charged by first electric power from anexternal power supply source through the second connector in a firststate and by second electric power from the antenna in a second state.9. The wireless communication device according to claim 8, wherein thefirst connector is a communication connector electrically connected tothe inner circuit.
 10. The wireless communication device according toclaim 8, wherein the electrical device further comprises a chargeswitching circuit electrically connected to the battery and the secondconnector.
 11. The wireless communication device according to claim 8,wherein the electrical device further comprises a wireless chargecontrolling circuit electrically connected to the battery and the firstconnector.
 12. The wireless communication device according to claim 11,wherein the wireless charge controlling circuit is configured totransform an electromagnetic wave received by the antenna into voltagecapable of charging the battery.
 13. The wireless communication deviceaccording to claim 11, wherein the wireless charge controlling circuitcomprises a rectifier circuit, a constant voltage circuit, a boostercircuit, and a diode.
 14. The wireless communication device according toclaim 8, wherein the battery is a lithium ion battery.
 15. The wirelesscommunication device according to claim 8, wherein the battery is adouble-layer electrolytic capacitor.
 16. A wireless communication devicecomprising: an electrical device comprising: a connector; a batteryelectrically connected to the connector; and an antenna connectable tothe connector, wherein the antenna is attachable to and detachable fromthe electrical device, wherein the battery is configured to be chargedby electric power from the antenna.
 17. The wireless communicationdevice according to claim 16, wherein the electrical device furthercomprises a wireless charge controlling circuit electrically connectedto the battery and the connector.
 18. The wireless communication deviceaccording to claim 17, wherein the wireless charge controlling circuitcomprises a rectifier circuit, a constant voltage circuit, a boostercircuit, and a diode.
 19. The wireless communication device according toclaim 16, wherein the battery is a lithium ion battery.
 20. The wirelesscommunication device according to claim 16, wherein the battery is adouble-layer electrolytic capacitor.